
NITROGENOUS FEEDING STUFES. 95 
through several months, conducted with the greatest accuracy, and involving 
many hundreds of analyses of fodder and milk, Kiihn concludes that, as soon as 
the amount of the ration exceeds a certain maximum, an increase is without 
effect upon the quality, and exercises only a slight influence upon the quantity 
of the dry substance of the milk produced. 
‘*This principle, first enunciated by Kiihn, has been confirmed by several 
experiments of similar character made by Wolff and Fleischer. Without going 
into details I will simply say that as the result of all their work these different 
experimenters come to about this conclusion. 
‘« By increasing the ration up.to a certain point the yield of milk may be in- 
creased, and not only the total yield but also the richness of the milk, the 
amount of dry substance, fat, casein, sugar, etc., may be thus increased. But 
at the same time the composition of this dry substance, the relative percentages 
of fat and casein remain the same even though the proportion of fat or albumin- 
oids in the food may be changed. 
‘Tt is very important, however, to notice that the amount of milk yielded 
and the variations produced by the food differs greatly with different breeds and 
individuals. That is to say, if I am feeding my cow a moderate ration, I may 
by adding thereto get more quarts of milk per day, and more casein and butter 
in a quart. But I may not expect to get a one-sided increase of butter by using 
oily food, or of casein by using more nitrogenous ration, When the fat is in- 
creased or decreased the casein changes in like proportion. 
‘“These results are very easily explained by the theory of the formation of the 
milk, lately propounded by the well-known physiologist Voit. This theory, 
which seems quite well supported by facts, assumes that the milk is not merely 
filtered from the blood through the lacteal glands, but is rather a product of a 
metamorphosis of the glands themselves. ‘The milk’ says Voit, *is essentially 
‘this organ liquefied by fatty degeneration.’ 
‘‘In this view, it is easy to see that when the cow is well fed and in good 
condition, there will be plenty of food for the formation of lacteal glands, and 
hence a plentiful production of milk, and that the composition of these would 
not be easily affected by variation of the composition of the food within ordinary 
ranges; and hence, why it should be so difficult by changes in the food to effect 
any change in the composition of the organic substance of the milk, Still it 
does not appear to be proven that a change in the quality of the food may not, 
in the course of months or years, or with the progeny, change the composition 
of the organic substance of the milk. 
‘There are, it is true, some exceptions to this rule. Some kinds of oily food 
have been observed to produce milk richer in fat. Indeed temporary changes 
in the composition of milk often follow changes in the food. But when experi- 
ments are repeated and long continued, and when the milk is subjected to re- 
peated and rigid analysis these changes are generally found to disappear. 
‘“ As regards the effect of different foods on the composition of the milk we 
may not hope by variation in the fodder to change a ‘casein (cheese) cow’ toa 
‘butter cow.’ We must rather depend for the quality of the milk, the relative 
richness in fat or casein, its special fitness for butter-making or cheese-making, 
upon the peculiarities of different breeds or different individuals, and for quan- 
tity upon the peculiarities of the animals themselves. Or, in few words, for 
quality of milk, select proper breeds; for quantity, good milkers.”’ 
